<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        div{
            width: 200px;
            height: 200px;
        }
        .d1{
            background-color: #477eff;
        }
        .d2{
            background-color: #a0ec2e;
        }
        .d3{
            background-color: #f695ff;
        }

        .son{
            width: 50px;
            height: 50px;
            background-color: #bdf4ff;
        }
        .son1{
            width: 50px;
            height: 50px;
            background-color: #bdf4ff;
        }
        .son2{
            width: 50px;
            height: 50px;
            background-color: #98ffb7;
        }

    </style>
</head>
<body>
    <!-- 基础外边距 -->
    <!-- 居中 -->
    <!-- 多值 -->
    <!-- 外边距重叠现象 -->
    <div class="d1">
        <!-- 外边距是否对文本生效？？？ -->
        <span>1</span>
    </div>
    <div class="d2">
        <div class="son">
            
        </div>
    </div>
    <div class="d3">
        <div class="son1">son1</div>
        <div class="son2">son2</div>
    </div>

    
</body>
</html>